When I am using the provider package in Flutter to load data from an API into a list it repeatedly calls the API, how do I fix it?

Question

I am trying to lode data from an api call that retrieves a map, I am able to get the map from the api to display how I want it to, however it repeatedly calls the api meaning the list keeps on refreshing. Even though I have tried setting the listener to false, it works but I have to manually refresh the app for it to work?

Additional Info: Assigning and Retrieving Data


import 'package:http/http.dart' as http;

class Stores with ChangeNotifier {

  var s_length;

  Future<List<Store>> getStores(String storeCatName) async {
    final queryParameters = {
      "store_category_name": storeCatName,
    };
    try {
      //TODO this is the issue - must fix.
      final uri = Uri.http("url", 'url', queryParameters);
      //print(uri);
      final response = await http.get(uri);
      //print(response.statusCode);
      //print(response.body);
      if (response.statusCode == 200) {
        final List<Store> stores = storeFromJson(response.body);
        _stores = stores;
        //print(_stores);
        print("lenght: ${_stores.length}");
        Store store;
        for(store in _stores) {
          store.products = Products().products(store.storeId);
        }
        //check if this is correct
        notifyListeners();
        //return stores;

      } else {
        print("error1");
        return List<Store>();
      }
    } catch (e) {
      print(e.toString());
      return List<Store>();
    }
    //notifyListeners();
    print(_stores);
  }

  List<Store> get favoriteItems {
    //return _stores.where((storeItem) => storeItem.isFavorite).toList();
  }

  bool isNotFull(){
    if (_stores.isEmpty){
      return true;
    } else {
      return false;
    }
  }

  int get numberOfStores{
    return s_length;
  }

  List<Store> _stores = [];

  List<Store> stores (String storeCatName){

    getStores(storeCatName);
    //print("cpp; + $s_length");
    //notifyListeners();
    return _stores;
  }

}

 final storesProvider = Provider.of<Stores>(
      context, listen: false
    );

    storesProvider.getStores(categoryName);

    final providerStoreList = storesProvider.stores(category.storeCategoryName);

Additional Info: Builder for List:

child: ListView.builder(
            itemCount: providerStoreList.length,
            itemBuilder: (context, index) => ChangeNotifierProvider.value(
                  value: providerStoreList[index],
                  child: StoreItem(),
                )));

If any additional information is required just let me know. Any help would be greatly appreciated.

Thanks

Please add the code where you are retrieving the data and where are assigning it... — Adarsh Srivastava, Feb 08 '21 at 05:07

score 0 · Answer 1 · answered Feb 08 '21 at 05:28

0

Use

listen: false;

   var ourClient = Provider.of<CartBlock>(context, listen: false);

answered Feb 08 '21 at 05:28

Tasnuva Tavasum oshin

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When I set listen to false, it doesn't load the data the first time . Instead I have to refresh the app using ctrl + s and then it will display as intended. – Adarsh Manoj Feb 08 '21 at 05:44
for this u need to call the provider in your init() method then 1st time it wont be a problem for you and then it will work , do listen false. – Tasnuva Tavasum oshin Feb 08 '21 at 06:00

score 0 · Answer 2 · edited Feb 08 '21 at 07:27

0

Setting the listener to false means that your widget won't build again when notifyListeners() is called.

So, that might not be the issue.

The only reason I can think of is calling the API again from the build method, which might happen if you are using a ListView builder. So, every time you might be scrolling the ListView your API would call again.

edited Feb 08 '21 at 07:27

Hasip Timurtas

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answered Feb 08 '21 at 06:39

Nitesh

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It is being called later in a ListView builder, so how would I then rectify this? – Adarsh Manoj Feb 08 '21 at 09:15
You should not use your stores() function in the ListView rather use a variable , so you get the already stored value, and not call the function which in turn calls your API. Also, adding your build method snippet would help. – Nitesh Feb 08 '21 at 10:49
@AdarshManoj I completely agree with HasipTimurtas...you should not call the getstores method in builder, calling it at the time of initState would help... – Adarsh Srivastava Feb 11 '21 at 06:30

When I am using the provider package in Flutter to load data from an API into a list it repeatedly calls the API, how do I fix it?

2 Answers2